BioMedical Admissions Test (BMAT) Practice Test 2026 - Free BMAT Practice Questions and Study Guide

The phenomenon of a lighted splint making a squeaky pop is indicative of the presence of hydrogen gas. When a lighted splint is brought near hydrogen, it reacts with the oxygen in the air, resulting in a small explosion or a "pop" sound. This is due to hydrogen's highly flammable nature and its ability to combust rapidly when mixed with air, leading to the characteristic noise produced during the reaction.

In relation to the other gases mentioned, oxygen would not produce a pop sound with a lighted splint; rather, a lighted splint would continue to burn more brightly in the presence of oxygen, as it supports combustion. Ammonia, on the other hand, has a distinct pungent odor, but does not react in a way that would cause a pop sound. Carbon dioxide, when introduced to a flame, would extinguish it, as it does not support combustion, thereby producing no sound. Thus, the response of the splint making a pop distinctly aligns with the presence of hydrogen.